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Minhaj Mehmood

Full Stack Developer

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Few days ago I’ve faced issue with domain which contains special characters such as www.schönesdresden.de. As of may-2010 it’s allowed to have top level domains in international language (e.g http://JP納豆.例.jp).

However, my task was to download the html using apache httpclient API therefore I have to use HttpGet(URI uri) class where-as java.net.URI could be any string which follows RFC 2396 rules (In short the domain names other than English are not considerable as valid URI) and finally I came across to following solution after couple of minutes searching on Google.


Basically first we have to convert the international domain name into ASCII Compatible Encoding (ACE) to pass it to HttpGet(URI uri) class for this purpose Java SE 6 provides an interesting new class: java.net.IDN It’s small, simple…very focused on a single task. That task has two parts:

  • To convert domain names from practically any Unicode character to an ASCII Compatible Encoding or ACE.
  • To convert ACE names back into their full Unicode UTF-16 encoding The toASCII method converts its non-ASCII Unicode characters to an ACE form using an algorithm called punycode.

For more details about punyode conversion check wikipedia link